Fuse plug assembly



June 15, 1937. SENER ET AL 2,084,222.

FUSE PLUG ASSEMBLY Filed April 9, 1936 2 Sheets-Sheet 1 George MB Seller T honuzs Mwman G. M. B. SENER ET AL 2,084,222

June 15, 1937.

FUSE PLUG AS SEMBLY 2 Sheets-Sheet 2 Filed April 9, 1956 11% 9E P Z 9 1? 101 1 f, H Z

\I: H 10 Z 4- a W (:9 0 1 0' 118 7 Wu e m aim!) George 11/155 A e/2 12W Thomas fi/em mafl ramed June 15, 1931 UNITED STATES PATENT OFFICE FUSE PLUG ASSEMBLY ,George M. B. Sen er, Pontiac, and Thomas Newman, Drayton Plains. Mich.

Application April a, 1936, Serial No. mm

140mm. (cl. zoo-11s) This invention relates to a fuse plug assembly and has "for its object to provide. in a manner as hereinafter set forth, whereby the elements therefor are so constructed and arranged relative 5 to each other as to prevent surreptitious tamperfng therewith. I i

A further object of the invention is to provide, in a manner as hereinafter set forth, a fuse plug assembly including a 'non-tamperable fuse and o adapter.

A further object of the invention is to provide,

in a manner as hereinafter set forth, a fuse plug assembly including a non-tamperable fuse plug cutout base.

5 A further object of the-invention is to provide, in a manner as hereinafter set forth, a fuseplugassembly having as an element thereof a nonremovable adapter.

A further object of the invention is to provide, in a manner as hereinafter set forth, a fuse plug assemblyhaving as an element thereof an adapter capable of being anchored in and nonremovable from a fuse plug cutout base or panel now generally employed in connection with a 55 fuse plug.

A further object of the invention is to provide,

in a manner as hereinafter-set forth, a fuse plug assembly including as an element thereof: an adapter formed of a pair of sections and with one of the sections forming an element of the block with which the fuse plug is associated.

Further objects of the invention are'to provide,

in a manner as hereinafter set forth, a fuse plug assembly which is comparativelygsimple in. its construction and arrangement, strong, durable,

compact, thoroughly efficient in its use, nontamperable and comparatively inexpensive: to

manufacture. a

To the above ends essentially and to others 40 which may hereinafter appear, the invention consists of the novel construction, combination and arrangement of parts as will be more specifically described and are as illustrated in the accompanying drawings wherein embodiments of the invention are shown, but it is to be understood that changes, variations and modifications may be resorted to which fall within the scope of the invention as claimed. 50 In the drawings:

Figure l is a front elevation of a fuse plug assemby in accordance with this invention, with the cover removed, A

Figure 2 is a section on line 2-2, Figure 1, 55 Figure 3 is a side elevation of the fuse plug,

Flgureiisaninvertedpianviewofthefuse p s I I Figure 5 is a side elevation of a modified form of fuse plug assembly, I

Figure 6 is a vertical sectional view of the form of assembly shown in Figure 5,

Figure 7 is a section on line 1-1, Figure 6,

Figure 8 is a top, plan view of the adapter forming an element of the assembly. shown in Fig Figure 9 is an'inverted plan view of one of the sections of the adapter shown in Figure 6,

Figure 10 is a perspective view of the fuse member as it would appear before being blown.

was reference to Figures 1 and 2 of the drawings, the assembly includes a substantially square fuse block generally indicated at I. andformed with rounded corners, The block is formed of an outer and an inner section II, II respectively. The said sections are of square vcontour. The

section I I includes an outer part iii and an inner part II. The said parts are of square contour. Vihe part II has rounded corners. extends laterally from each of the sides of the part II. The part II is formed with four equally spaced aligning circular sockets II, only two of p which are shown. The sockets open at the outer face-of the part II. The latter is also provided with four semi-oval shaped sockets II extending laterally from and communicating with the sockets II. The width of the sockets il isma- 'terially less than the diameter of the sockets It.

The sockets ii are arranged in opposite extending pairs. The bases of the sockets l6 and I1 align'with the upper face of the part ll. 7

The part it has its upper face formed with The part'll' four circular cutouts It (only two of which are shown) The cutouts ll are disposed concentrically with respect to and are of less diameter than the sockets II. The cutouts i8 communicate with the sockets it through the bases of these latter. The part It is formed with four annular grooves I! (only two of which are shown). The

grooves I! are arranged inwardly with respect to the cutouts II. The outer walls II of the grooves ll form continuations of the walls of the cutouts II. The depth of the grooves is is less. than half the thickness of the part ll. The latter is formed with four circular I! (only two of which are shown) and they are arranged to align with the axes of the sockets it. Each e 2! is disposed centrally with respect to.

"a cutout It. The wall of each passage fl is upon. two different diameters, the smallest of which is indicatedat 22 and the largestat II. 'Iheiunotion of the different diameter wall portions of the passages 2| provides the part H with internal shoulders 24. The edges of the portions of the part |4 between the inner walls of the grooves l9 and the wall portions 22 are toothed, as at 25. The part l4, in its lower face, is formed with an annular groove 26. The part I4 is formed with four openings 21' (only two of which areshown) which extend from the bases of the sockets II to the top wall 26 of groove 26. The lower face of the part |4-is provided with four annular grooves 29 (only two. of which are shown) and said grooves 29 are materially iess inde'pth than the groove 26. Each groove 29 encompasses in spaced relation the inner end of a passage 2|. The upper face of part i4 is provided with three spaced pairs of spaced cutouts. The cutouts of one pair are indicated at 30, 3|, the cutouts of another pair at 32, 33 and the cutouts of the other pair at 34, 35. The purpose of said cutouts will be presently referred to. The bottom of part i4, axially thereof, is formed with a squared lug 36.

The section I2 is of square contour and has its edges flush with the edges of the part H of section The section l2 has the marginal portion of its outer face rabbeted throughout, as at 31. The outer face of the section |2, inwardly of the rabbet 31, is cut out, as at 38, and communicating with said cutout are four rectangular sockets 39 (only two of which are shown). The outer face of the section I2 is formed with a pocket 40 arranged between the inner ends of the sockets 39.

The portion 4| of the part I4 is mounted in the rabbet 31 and is provided with Screw threaded openings 42. The portion 43 of the section |2 extends into the groove 26 and is spaced from the top or outer wall 28 of groove 26. The portion 44 of part |4 extends into the cutout 38 oi section l2. The lug 36 extends into pocket 40. The inner ends of the passages 2| open into the sockets 39 centrally of the latter.

The part I3 is integral with the part I 4. The part I4 is independent of the section H. The part l4 and section |2 are connected together by the holdfast means 45. The block I0 is formed with openings 46 at its corners. The openings 46 extend through the part I4 and section l2 and are adapted to receive suitable holdfast means for anchoring the block ID to a support.

Mounted against the base or inner wall of each socket 6 is an annular contact member 41 having its inner edge flush with the wall of the cutout l8. Integral with and extending from the outer edge of the contact 41 is a semi-oval shaped apertured stem 48 which is seated upon the base or inner wall of a socket Mounted upon the base of the cutout 30, cutout 3|, cutout 34 and the cutout 35 is a conducting plate 49 which extends into the groove 26 and has its inner portion aligning with stem 48. Each stem 48 is electrically connected to a plate 49 by a threaded headed metallic holdfast device50 which extends through an opening 21 and engages in the plate 49. The plates 49 are spaced from section |2 by the portion 4| of part |4. anchored to the portion 4| of part M by a threaded holdfast device 5| which has threaded engagement with an opening 42-and abuts against the outer face of section l2. The plates 49 and holdfast devices 5| provide terminals for circuit wire connections not shown.

Carried by and arranged in the inner face of the portion 44 of the part I4 are four annular The plate 49 is contacts (only two of which are shown) and which are arranged in pairs. The annular contacts of each pair are disposed in spaced alignment. The annular contacts of the pair shown are designated 52, 53 and the said four annular contacts are mounted in the grooves 29 and extend into the sockets 39, as well as being arranged in the path of circuit closures to be presently referred to. The annular contacts 52, 53 of each pair are electrically connected together by a strip of conducting material 54 as represented by the dotted line showing, Figure l. The annular contact 53 of each pair is provided with an outwardly directed stem 55 of conducting material. The stems 55 are of a length to extend into the cutouts 32, 33 at the inner ends of the bases of these latter and are connected by the holdfast devices 56 to the portion 4| of part H. The stems 55 and holdfast devices 56 provide terminals for circuit wire connections.

Within each of the sockets 39 is arranged a rectangular shiftable circuit opening and closing member 51 which is to bridge and coact with a contact 52 or 53. Carried by the member 51 is a threaded stem 58 which operates through the passage 2|. Surrounding the stem 58, abutting the member 51 and also abutting the shoulder 24 is a coiled controlling spring 59 which functions when the member 51 is released in a manner to be referred to to shift the member 51 clear of the contact 52 or 53. The stem 56 is peripherally threaded.

The lug 36 is to prevent flash over from contact 52 to contact 53.

When all stems 58 are released, the fuse block or fuse panel is absolutely dead front.

A contact 52 and 53, apassage 2|, a groove I9, a set of teeth 25, a cutout l8 and a socket 39 constitute the stationary section of an adapter. The latter is formed of two sections, one the stationary section referred to and the other a movable section consisting of a circuit opening and closing member 51, a stein 58 and a spring 59.

The block I0 as shown, will be provided with four adapters and there will be associated with each adapter a fuse plug which is to be detachably connected with the adapter. Owing to the manner in which the adapter is set up it cannot be tampered with. The fuse plug is generally indicated at 60 and includes a body part 6| formed of porcelain, Bakelite or other suitable non-conducting material. The body part 6| is of tubular form and is provided with a socket 62 opening at its outer end. The socket 62 is of materially less length than that of body part 6| and has its inner portion, indicated at 63, gradually decreasing in diameter towards its inner end. The inner or base wall of socket 62 is indicated at 64. The body part-6|, at its outer end, is formed with a laterally disposed annular flange 55 having its edge provided with diametrioally disposed grooves 66 of like form and each includes a pair of side walls and an inner wall. Each side wall has a narrow outer portion and a wide inner portion. The inner wall includes an outer straight portion and an inwardly inclined inner portion. The outer portion of the side walls merge into the outer straight portion of the inner walls. The wide inner portions of the side walls merge into the inclined inner portions of the inner wall. The inclined portions of the inner walls are indicated at 61. The body part 6| has a reduced inner portion 70 thereby a peripheral forming said body part 6| with shoulder 1 I. The inner end of the reduced portion 18 of the body part 8| is formed with a socket 12 and with teeth 18. The body part 8|,

axially thereof, is formed with a circular bore 14'which extends from the base 54 of socket 82 to the base of socket 12. Anchored to the bore 14 is an interiorly threaded tubular member 15 open at its inner end, toothed on its. inner-edge, as at 15, (Figures 1 and 4) and which merges at its outer end into a disc 15, of greater diameter than said member. The disc 16 seats upon the base 54 of socket 52. A fuse element, indicated at 11, includes a flat stretch 18 seated upon the disc 15 and a curved stretch 18 merging at one end into one end of the stretch 18 and at its other end-into a stretch 88 embedded in the body part 5|. annulus 8| which forms 'a part of element 11, surrounds the reduced portion 18. and bears against the shoulder H. The stretch 18 of the fuse element 11 is anchored upon and to the disc 15 by a body 82 of cementitious material. Seated upon the outer end of body part 5i is a transparent closure 88 for the outer end of the socket 52. A retaining cap for the closure is indicated at 84 and which is formed with inherent diametrically opposed bendable arms 85 for mounting in the grooves 55 and bent to engage the wall portion 51 of the grooves 55 whereby the closure 88 and cap 84 are connected to body part 5|. The element 11 has spaced weakened parts. I

When the fuse plug 58 is connected to the block I8 the member 15 extends upon the stem 58 and on revolving plug 58 the threads of member 15 will coact with the threads on stem 58 to provide for the shifting of member 51 'to the position shown in Figure 2, whereby said member 51 will engage with a contact 52 or 53 and such position of member 51 will be had against the action of spring 58. When plug 58 is seated in the I block I8 it is arranged in co-relation with respect to the adapter. The reduced inner end 18-of body part 5| will extend into cutout I8 and also into the groove I8. The annulus 8I,.which surrounds the reduced portion 18 of body part 5| will seat against a contact. When the fuse plug 58 is coupled to the block I8 the inner end edge of the portion 18 will oppose and be spaced from the inner wall of groove [8. When the fuse plug 88 is connected to the block I8 a portion of part I4, indicated at 85, will extend into the socket12. i

When the fuse plug 58 is connected to the block the teeth 18 will extend inwardly beyond and in surrounding relation with respect to the teeth 25. The teeth 25 will be arranged outwardly beyond and in surrounding relation with respect to the teeth 15'. The teeth 25, 13 and 15 function to tear or disrupt any foreign body or bodies, such as lead foil, small wire, etc. that may be placed in the fuse 58, socket I5 or part I4 of block I8 or an adapter 88 to be referred to for the purpose oftampering with the fuse plug assembly.

The fuse plug assembly shown in Figures 3 to 9 is of the type for connection to the form of fuse block or panel now in general use. The assembly shown in Figures 5 and 6 is generally indicated at 81 and consists of a fuse plug 88 and an adapter 88. The fuse plug 88 is of the same construction as the fuse plug 58 and the description of the latter is to apply to the description of the plug 88. The adapter 88 is of a type which is to be The stretch 88 merges into an secured in a non-removable position with respect to the block or panel in which it is to be extended. The adapter 88, when in secured position, cannot be tampered with. The adapter 88 includes a threaded sleeve 88 of conducting material formed with a pair of diametrically opposed rectangular slots 8I, 82 in proximity to its inner end. The sleeve 88, at its outer end, is formed with an inwardly extending annular flange 83. The sleeve 88 encompasses the body part of the adapter and said body part consists of a forward and a rear section 84, 85 respectively, arranged in endwise abutting relation and formed of porcelain, Bakelite or other suitable non-conducting material. The section .84, at its outer end, is formed with a circular cutout 85 which corresponds to the cutout I8 formed in the part I4 of the block I8. The section 84 is provided with an annular groove 81 which opens into the cutout 88 and which corresponds to a groove I8 in the part I4 of the block I8. The outer wall 81 of groove 81 is flush with the wall of the cutout 85. The section 85 has its rear end provided with a rectangular socket 88 in which is arranged a yoke-shaped member 88 of conducting material having its arms I88 extended forwardly and provided at their forward ends with oppositely disposed inwardly extending flanges I8I which seat in grooves I82 formed in the forward or base wall of the socket 88. A yoke-shaped insulating member I83 is mounted against the inner sides and forward face of the base of the member 88. The member I88 is spaced from the flanges I82 and said flanges constitute contacts and extend into the socket 88 in the path of a shiftable spring controlled circuit closure to be presently referred to. The section 84 has an axial bore I84 with its wall formed of two different diameters. The larger diameter wall portion is indicated at I85 and opens into socket 88 and the smaller diameter wallportion is designated I85 and communicates with the cutout 85. The junction of the two diameters of wall portion provides the section 84 with an internal shoulder I81. The section 84, at a point thereof bordering the outer end of the bore I84 and the inner wall of the groove 81, is formed with a row of teeth I88.

The section has an axial opening I88 through which extends a holdfast means II8 threadedly engaging in the base of the member 88.

Shiftable within the socket 88 is a spring controlled circuit opening and closing member or element III for engaging with the flanges I82 for the purpose of closing the circuit. Integral with the member II I and extending through the bore I84 is a peripherally threaded stem H2 for threaded engagement with the interiorly threaded tubular member II8 of the fuse plug 88. Interposed between the shoulder I81 and the member III as well as surrounding the stem 2 is a coiled controlling spring II4 for the member II I. The spring I I4 functions to shift the member I I I clear of the flanges I82 when the stem H2 is released from the tubular member I I3. The latter functions in connection with the threads of the stem to shift the member III to and to hold it in circuit closing position relative to the flanges I82.

The section 84 has arranged therein a pair of oppositely disposed spring. controlled locking members H5, H5 provided with pointed locking barbs H1, H8 for extension through the slots 8|, 82 respectively and which are capable of enin which the adapter 89 is mounted for the purpose of locking the adapter 89 to prevent it from being removed and from being tampered with.

The adapter shown in Figure 6 is substantially the same in construction as the adapter shown in Figure 2 with the exception that the construction ltl will provide the flanges instead of an annulus. The fuse plug 88 is arranged relative to the adapter I! in the same manner as the fuse plug 80 is arranged relative to an adapter shown in Figure 2.

With reference to Figure 2, the part ll of-the block I is provided with a ground attachment bar, as indicated at I20, to which all neutral wires are attached.

Each contact 41 is an outer contact or outer contact means. Each contact 52 or 58 is an inner contact'or inner contact means. The flange I3 is an outer contact or outer contact means. The flanges ill provide an inner contact or inner contact means.

The threaded holdfast devices 50 are exposed when panel cover is open for the purpose of testing and replacing fuses. i

The fuses intended to be used will have threads of a different pitch on those up to 15 amperes capacity than those fuses of a capacity of 30 amperes. This is to prevent the use of a 30 ampere fuse where the value should-only be or amperes.

What we claim is:

1. In a fuse plug assembly, a rotatable pluglike element of non-conducting material, said element being formed with a socket and an axial opening communicating with the socket, said element being formed with a peripheral shoulder, a fixed interiorly threaded tube in said opening and having a closed end positioned within said socket, a fuse anchored to said end, arranged in said socket, extending through the plug body and abutting said shoulder, and an adapter structure for receiving said element, said structure including abody of non-conducting material formed with a socket and a passage opening into the latter for receiving said tube, an outer contact on said body for coaction with said fuse, a shiftable spring controlled circuit opening and closing member within the socket of said body, an inner contact for coaction with and normally free of contacting relation with said member, and a peripherally threaded stem carried by said member, arranged in said passage for threaded engagement with the threads of said tube, on the rotation of said element in one direction to provide respectively for the coupling of said element and body together; the shifting of said member to engage said inner contact; and for the contacting of the fuse with said outer contact.

2. In a fuse plug assembly, a rotatable plugiike element for coupling to an adapter, said element being formed with a socket and an axial opening having one end communicating with said socket, said element being formed with a peripheral shoulder, a fixed interiorly threaded tube in said opening adapted to threadedly engage with the adapter to couple the latter and element together, said tube having a closed outer end arranged within said socket, said tube having an open inner end, a fuse having a stretch anchored to said closed end, a stretch arranged in said socket, a stretch extending through the body of said element and a stretch arranged against said shoulder, said tube having a portion extended inwardly from the other end of said opening.

3. In a fuse plug assembly, a rotatable pluglike element for coupling to an adapter, said element being formed with a socket and an axial opening having one end communicating with said socket, said element being formed with a peripheral shoulder, a fixed interiorly threaded tube in said opening adapted to threadedly engage with the adapter to couple the latter and element together, said tube having a closed outer end arranged within said socket, said tube having an open inner end, a fuse having a stretch anchored to said closed end, a stretch arranged in said socket, a stretch extending through the body of said element and a stretch arranged against said shoulder, said tube having a portion extended inwardly from the other end of said opening, said socket opening at the outer end of said element, said element being formed with a socket opening at the inner end thereof and having its,

wall encompassing in spaced relation the extended portion of said tube.

4. In a fuse plug assembly, a rotatable plug-like element ior coupling to an adapter,

shoulder, a fixed interiorly threaded tube in said opening adapted to threadedly engage with the adapter to couple the latter and element together, said tube having a closed outer end arranged within said socket, said tube having an open inner end, a fuse having a stretch anchored to said closed end, a stretch arranged in said socket, a stretch extending through the body of said element and a stretch arranged against said shoulend of said element, with a socket opening at the inner end thereof and having its wall encompassing in spaced relation the extended portion of said tube, and said element being formed at its inner end with a row of teeth encompassing in spaced relation the extended end of said tube.

5. In a fuse plug assembly, a rotatable "pluglike element for coupling to an adapter, said element being formed with a socket and an axial opening having one end communicating with said socket, said element being formed with a peripheral shoulder, a fixed interiorly threaded tube in said opening adapted to threadedly engage with the adapter to couple the latter and element together, said tube having a closed outer end arranged within said socket, said tube having an open inner end, a fuse having a stretch anchored to said closed end, a stretch arranged in said socket, a stretch extending through the body of said element and a stretch arranged against said shoulder, said tube having a portion extended inwardly from the other end of said opening, said element being formed with a laterally extending flange at its outer end having its edge formed with grooves. the inner walls of said grooves having inwardly extending inclined parts, said socket opening at the outer portion of said element, a transparent closure on the outer end of said element for said socket, and means for securing said closure to said element, said means having inherent parts binding against said walls for anchoring it to said element.

6. In a fuse plug assembly, an adapter for coupling to the plug of the assembly, said adapter including a body of non-conducting material formed with a socket, a cutout at its outer end, a groove opening into said cutout and a passage communicating at its innerend with said socket and at its outer end with said cutout, an outer contact at the outer end of said body bordering said cutout, an inner contact at the inner wall of said socket, a spring controlled circuit opening and closing member within said socket for coaction with and normally free of contacting relation with said inner contact, and a shiftable structure for and carrying said member, said structure including a peripherally threaded plug engaging element extending through said passage for threadedly engaging the plug for coupling the latter to the adapter.

'I. In a fuse plug assembly, an adapter for coupling to the plug'of the assembly, said adapter including a body of non-conducting material formed with a socket, a cutout at its outer end, a groove opening into said cutout and a passage communicating at its inner end with said socket V and at its outer end with'saidcutout, an outer contact at the outer end of said body bordering said cutout, an inner contact at the inner wall of said socket, a spring controlled circuit opening and closing. member within said socket for coaction with and normally free of contacting relation with said inner contact, a shiftable structure for and carrying said member, said structure including aperipherally threaded plug engaging element extending through said passage for threadedly engaging the plug for coupling the latter to the adapter, and said body being formed with a row of teeth bordering said opening and groove.

8. In a fuse plug assembly, an adapter for coupling to the plug of the assembly, said adapter including a body of non-conducting material formed with a socket, a cutout at its outer end, a groove opening into the cutout, a passage communicating at its inner end with said socket and at its outer end with said cutout, a threaded shell of conducting material encompassing said body and having an inwardly extending flange at its outer end constituting an outer contact seated against the outer end of said body and-bordering said cutout, an inner contact at the inner wall of said socket, a spring controlled circuit opening and closing member within said socket for coaction with and normally free of contacting relation with said inner contact, and a shiitable structure for and carrying said member, said structure including a peripherally threaded plug engaging element extending through said passage for threadedly engaging the plug for coupling the latter to the adapter.

9. In a fuse plug assembly, an adapter for coupling to the plug of the assembly, said adapter including a body of non-conducting material formed with a socket, a cutout at its outer end,

a groove opening into the cutout, a passage communicating at its inner end with said socket and at its outer end with said cutout, a threaded shell of conducting material encompassing said body and having an inwardly extending flange at its outer end constituting an outer contact seated against the outer end of said body and bordering said cutout, an inner contact at the inner wall of said socket, a spring controlled circuit opening and closing member within said socket for coaction with and normally free of contacting relation with said inner contact, a shiftable structure for and carrying said member, said structure including a peripherally threaded plug engaging element extending through said passage for threadedly engaging the plug for coupling the latter to the adapter, and said body being formed with a row of teeth bordering said opening and groove.

10. In a fuse plug assembly, an adapter for a coupling to the plug of the assembly, said adapter including a body of non-conducting material formed with a socket, a cutout at its outer end, a groove opening into the cutout, a passage communicating at its inner end with said socket and at its outer end with said cutout, a threaded shell of conducting material encompassing said body and having an inwardlyextending flange at its outer end constituting an outer contact seated against the outer end of said body and bordering said cutout, and inner contact at the inner wall of said socket, a spring controlled circuit opening and closing member within said socket for coaction with and normally free of contacting relation with said inner contact, a shiitable structure for and carrying said member, said structure including a peripherally threaded plug engaging element extending through said passage for threadedly engaging the plug for coupling the latter to the adapter, said shell being formed with spaced slots, and oppositely disposed spring controlled locking devices carried by said body and extendible through said slots.

11. In a fuse plug assembly, an adapter for coupling to the plug of the assembly, said adapter including a body of non-conducting material formed with a socket, a cutout at its outer end, a groove opening into the cutout, a passage communicating at its inner end with said socket and at its outer end with said cutout,'a threaded shell of conducting material encompassing said body and having an inwardly extending flange at its outer end constituting an outer contact seated against the cuter end of said body and bordering said cutout, an inner contact at the inner wall of said socket, a spring controlled circuitopening and closing member within said socket for coaction with and normally free of contacting relation with said inner contact, a shiftable structure for and carrying said member, said structure including a peripherally threaded plug engaging element extending through said passage for threadedly engaging the plug for coupling the latter to the adapter, said body being formed with a row of teeth bordering said opening and groove, said shell being formed with spaced slots, and oppositely disposed spring controlled locking devices carried by said body and extendible through said slots.

12. In a fuse plug assembly, a fuse block formed of inner and outer interengaging connected together sections of non-conducting material, said outer section being formed in its outer face with a pair of outer sockets arranged in lateral communicating relation and with one of greater area than the other, a cutout inwardly of and opening into the socket of greater area through the bottom of the latter, an outer groove inwardly of and opening into the cutout through the bottom of the latter, an inwardly directed passage extending from said cutout, an inner groove in its inner face, a rear groove encompassing said passage adjacent to said inner groove, an opening leading from the outer socket of smallest area to said inner groove and a pair of spaced vertical cutouts communicating at their bases with said inner groove: and said inner section beingformed on its outer face with an inherent part of less depth than and extended into said inner groove, and a rear socket into which said passage and rear groove open.

13. In a fuse plug assembly, a fuse plug block formed of a. body of non-conducting material provided with an outer and an inner socket and communicating means between said sockets, said outer socket for receiving the fuse plug, an outer contact in the form of an annulus seated upon a wall of the outer socket and for coaction with the fuse of the plug, an inner contact in the form of an annulus mounted in a wall of the inner socket, a conductor positioned in said body connected to the inner contact, a second conductor in said body, means for electrically connecting said second conductor to said outer contact, a spring controlled circuit opening and closing member within said inner socket for coaction with and normally free of contacting relation with said inner contact, and a shiftable structure for and carrying said member, said structure including a peripherally threaded element operating in said communicating means for coupling the plug to the block.

14. In a fuse plug assembly, a fuse plug block formed of a body of non-conducting material provided with an outer and an inner socket and communicating means betwen said sockets, said outer socket for receiving the fuse plug, an outer contact in the form of an annulus seated upon a wall of the outer socket and for coaction with the fuse of the plug, an inner contact in the form of an annulus mounted in a wall of the inner socket, a conductor positioned in said body con nected to the inner contact, a second conductor in said body, means for electrically connecting said second conductor to said outer contact, a spring controlled circuit opening and closing member within said inner socket for connection with and normally free of contacting relation with said inner contact, a shiftable structure for and carrying said member, said structure including a peripherally threaded element operating in said communicating means for coupling the plug to the block, and said communicating means being formed to receive the inner end of the fuse plug when the latter is coupled to the block by said element.

GEORGE M. B. SENER. THOMAS NEWMAN. 

